The chemical and enzymatic synthesis of a series of oligo- and polyribonucleotides as potential antitumor and antiviral agents is to be undertaken. The compounds will be evaluated for interferon-inducing ability as well as antiviral and antitumor activity. New techniques including polymer support systems and photolabile protecting group utilization will be developed for the chemical synthesis of oligoribonucleotides. Comparison of helix stability, chemical modification and biological activity will be studied for a series of polynucleotide complexes.